Experimental allergic encephalomyelitis (EAE) is an animal model for multiple sclerosis (MS) and acute disseminated encephalomyelitis; and it is specially useful to study the mechanism(s) involved in autoimmune disorders in general and neuroimmunological dysfunction in particular. There is ample evidence that in MS patients immunoregulation is defective. Interferon (IFN) is now known to be an immunomodulatory agent and its intrathecal injection into MS patients has been reported to reduce exacerbations. We have evidence for a suppressive effect of IFN on the course of EAE. Here we propose to undertake a pilot study on the effect of intracerebrally injected IFN on the course of the passive and active forms of EAE. IFN will be administered either prophylactically or therapeutically via the IV or lateral ventricle. IFN delivery will be through implanted miniosmotic pumps. The effects of IFN will be followed by monitoring clinical signs of the disease as well as by histological analyses of brain and spinal cord specimens. Control rats will be treated and analyzed similarly, they will be however injected with "mock" IFN. In the short term the information obtained will be invaluable as a correlate to information obtained with actual IFN-MS trials now underway. The long term goals are to gain an understanding of the basic mechanism(s) by which IFN is able to suppress the immune system and thus have a sound basis for establishing therapeutic protocols and strategies for neuroautoimmunity and other immune dysfunctions.